If competitive elections are the backbone of our democratic republic, U.S. House elections are the snails: no vertebrae, only a hard, protective shell of their own making. More than 80 percent of members are safe within the shell of one-party districts where they’re never tested by a challenge from the opposing party, and they rarely face a serious primary challenge.

The result is a breakdown of the accountability system intended to bind representatives to their constituents. Instead, voters increasingly are chained to an unpopular and unresponsive Congress. We founded the nonpartisan Campaign for Primary Accountability to unchain the voters by addressing this lack of electoral accountability.

CPA began with the premise that greater voter participation is the key to breaking the gridlock in Washington. Greater participation means members in one-party districts will be accountable to a broader cross section of voters, instead of a narrow spectrum of vocal activists and a small circle of Washington insiders.

In 2012, we set out to demonstrate how to fix the broken system by equalizing spending between primary challengers and incumbents, and encouraging more voters to cast a ballot in the primary. No one to our knowledge had ever tried this approach.

And it worked. In the 2012 races where an incumbent faced a nonincumbent challenger (the only type of race we’ll most likely see in 2014), our record was nothing short of astonishing. If a challenger spent $250,000 and CPA spent $200,000 in both messaging and ground operations, we had a 100 percent track record of success.

How did we do that? First, our super PAC spending in those races neutralized the typical funding advantage enjoyed by incumbents. Second, we were able to increase turnout on average by 22.4 percent in the districts where we were engaged. This played a significant role in the outcome of several races. For example:

Voters in Ohio’s 2nd District primary participated in greater numbers than virtually any other congressional district in the state. Republican primary turnout was up 48 percent over 2010, and these “new” primary voters broke strongly for challenger Brad Wenstrup, the Iraq veteran who scored a stunning upset victory.

In the 16th District of Texas where CPA backed Democratic El Paso Councilman Beto O’Rourke, 20,000 more people cast ballots in the 2012 primary than in 2010 — an increase of 76 percent. These voters provided O’Rourke with his 300-vote margin of victory over the incumbent.

Both Wenstrup and O’Rourke went on to win their general election handily — no surprise as their districts are typical, dominated by a single party.

The record is clear: When more people engage in primaries and the spending gap between incumbents and challengers is equalized, voters are able to hold their elected representatives accountable.

Armed with this track record of success, CPA is planning to aggressively engage in House primaries of both parties in 2014.

Several factors make the 2014 cycle even more favorable to challengers. First, midterm elections have lower turnouts, traditionally a negative for challengers. But CPA showed how to make low-turnout primaries work to the challenger’s advantage. In 2012, CPA worked to identify general election voters and motivate them to cast a ballot in the primary. And it worked.

The lessons of 2012 are promising for a renewal of accountability in 2014. Would-be challengers see it is possible to take on entrenched incumbents and win. Voters see that their participation has an outsize impact in primaries. And smart political operatives now know that boosting voter turnout is a clear path to victory for challengers.

The ripple of primary challenges we saw in 2012 could become a wave in 2014. And the Campaign for Primary Accountability will be there with the experience and know-how needed to hold incumbents accountable to their constituents.

Leo Linbeck III is president and CEO of Aquinas Cos., LLC and founder of the Campaign for Primary Accountability, a nonpartisan super PAC active in House primaries.